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Author Topic: Why Has It Not Rained In The Atacama Desert For 40 Million Years ?  (Read 25076 times)

Offline neilep

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Dearest Desertologists,

I'm not a particular fan of dessert..I'd rather have a horses-dervrerr than ice cream !!....but I do enjoy a drink of water.....Something that I will find very little of in this place !





The Atacama Desert At The Very Time That These Photos Were Taken... ::)




Apparently, there are parts of this desert that have not seen any rain at all for 40 million years !!!

A few questions:

Why has it not rained there for 40 million years ?

How do they determine the length of time since it last rained ?

With the crazy weather that happens globally how can parts of the Atacama desert remain consistent in a weather orientated kind of way ?

Is there no life there at all in those water baron areas ?

D'ya think they'd be an explosion of plant life if it rained there ?



whajafink ?




Hugs & shmishes



mwah mwah



neil
If Desmond Had A Pain, He Would Be Des-Hurt *le groan*
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Offline Geezer

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Obvious really. It's so freekin' cold there that the only precipitation is snow.

You can clearly see the snow in the first picky.

Next question please!
 

Offline neilep

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If the only precipitation is only as snow..then..after 40 million years they'd be a lot of it yes ?
 

Offline Geezer

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Um, er, well, yes  ;D
 

Offline latebind

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If the only precipitation is only as snow..then..after 40 million years they'd be a lot of it yes ?

Perhaps it melted?
 

Offline neilep

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Doers it get warm enuff for any snow that fell to melt ?..It's quite high up I think !
 

Offline Geezer

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Maybe you should move this thread so the Geoillogical chappies can have a go at it?

BTW - where is this place?
« Last Edit: 05/01/2010 18:29:06 by Geezer »
 

Offline Madidus_Scientia

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It seems to be on Mars :p Or at least it looks like it, the place is often used to film Mars scenes in movies. But it's on the coast of South America west of the Andes mountains
« Last Edit: 06/01/2010 05:44:19 by Madidus_Scientia »
 

Offline Don_1

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I think M_S has explained why this desert is one of the dryest. It is shaded by the Andes and the Chilean Coast Range.

Moisture laden air coming off the Atlantic is 'trapped' by the Andes on the west side, where it precipitates on the Amazon rain forest. By the time this air gets over the Andes, it has little moisture left and what is left, is retained by the warming air.
 

Offline Bored chemist

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It hasn't rained there because I haven't tried to organise a barbecue there.
OK so it's dry because it's in the rain shadow of two mountain ranges but how do they know it hasn't rained for so long?
 

Offline Don_1

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They asked Michael Fish?

I can only guess that any rain would have left impurities behind, which may be able to be dated by geological strata or perhaps carbon dating.

I tried carbon dating once, ended up on a date with a stick of charcoal.
 

Offline JimBob

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Neil, I hate to break it to you but the desert formed only about 14 Million years ago. And it does get some rain. The evidence for this is dating of the sediments - fossil pollens and other things, such as insects blown into the area, are some of the several methods for dating the last rainfall. Some areas do get rain - about one millimeter a year.

I Agree. The white is rock - part of the geology. Or, it is possibly nitrates from bird dropping but in this particular area which is the driest part, I doubt it. (I remember National Geographic pictures for some reason.) 
 

Offline Geezer

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See! I told you to move this thread to the Geoideaillogical section.
 

Offline neilep

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Thank ewe DiscoverDave for your very much appreciated and informative post. ..and well done on your sponsorship of a child too !!
Great information !..Thank you very much indeed, that's great stuff !

JimBob...equally so I thank ewe...though, your apparent laziness to not provide pictures demonstrates perfunctoral insouciance ! ;)...I DID say that my question applies to some parts of the Atacama...though 1mm a year in some parts is hardly worth building an ark eh ? Still, your knowledge is welcome and is said with such aplomb and authority that I am filled with gratitude.

Jim, what was their before the desert ?

Thanks also to Madidus_Scientia, Don1 and BC who really ought to test his theory and in fact arrange a barbecue

Geezer....Shall I move it then ?
 

Offline Geezer

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Nah! It's fine where it is.

Interesting topic though.
 

Offline JimBob

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"Jim, what was their before the desert ?"


IN THE BEGINNING ...
 

Offline stereologist

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The white layer could be volcanic ash. It looks a lot like Death Valley in California. They evaporation rate in Death Valley is 150 inches a year. Flood the place with 4m of water and it will all be gone in one year. If this desert in the Andes is similar then any water falling would be hard to find.
 

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